Airdog Lift Pump install to Cummins ISL

[DW SD]

My Factory Cummins startup lift pump was leaking. This primes the CAPS injection pump for 30 seconds before stopping. From there the CAPS injection pump draws fuel itself.

In my process of researching the issue many ISL threads suggested the CAPS injection pump apparently is very sensitive to air and fragile. Any air could cause it to fail.
This pump will run always when the ignition is switched on. It appears very well made and is rated to pump 100 gallons per hour.

Providing pressure fed fuel to fragile injection pump was the goal, hopefully improving the CAPS injection pump’s reliability.

I had them set the onboard airdog pressure regulator at 17 psi. Which is similar to startup lift pump from what I’ve read.

This setup was about $550, $339 for the pump from PureFlow (airdog manufacturer) and $214 for hose and hose ends from my local hotrod plumbing shop. A new cummins lift pump was $300. So I figured I’d spend a bit more hopefully for the reliability upgrade.

Like the original install the pump sits between primary and secondary filters. I fabbed my own standoff mount from 3/16” x 2” angle steel and 1/8” plate.

Remaining are the electrical connections which I will add to the PDU. I will add a Bosch cube relay and trigger via ignition switches 12V which is readily available there.

I also bought a metric pack connector and installed that to the pump and harness and some gland nuts which I will add 1 to the PDU to keep it water tight.

I capped off the old lift pump fittings with -10AN caps.
Note all hose and hose ends are -10AN. Except the return to the tank which is -8AN.
I will try and add some photos of the old lift pump connections with the caps. Those that I took were too dark. The flash didn’t operate on my phone.

Others who installed a similar constant flow lift pump setup claim a more stable idle and even less lag under load. I guess if the engine were fuel starved this might result. While I’m skeptical of that, if I end up with a more reliable engine I will be happy with the upgrade.

I plan to install a switch to trigger the relay manually. The setup could be used as a fuel polisher and then run without the ignition switch being on.

Cheers,

Doug

[Randy Dupree]

Looks factory to me.
I think your being smart to add that pump.

[DW SD]

Originally Posted by Randy Dupree

Looks factory to me.
I think your being smart to add that pump.

Thanks Randy

Doug

[Dc2x4drvr]

Nice job!

[NoGas]

Sweet job!

Provided incentive for me to go back 4 years and reread DonB’s broken down thread. Some excellent lessons on handling adversity there.

Yet another project for an already too long “To Do” list.
.

[Craig Clark]

Great job & high marks on the spotless engine bay!

[DW SD]

Originally Posted by Craig Clark

Great job & high marks on the spotless engine bay!

Thanks Craig and Van and Lance!!
I’m optimistic this will work very well.
Doug

[DW SD]

Yesterday, I finished up the wiring for the new fuel pump. I flipped over the relay and fuse panel for the pump. I tapped in to the the output from the ignition ECU relay (lower left corner of relay panel). And used that as the trigger for the new relay I installed (hanging from lower right corner of relay panel).
I used Morris butt-connectors and adhesive lined shrink tubing for all connections.
The fuel pump turns on and off with switched ignition now.
Had I had the right wire terminal ends, I could have added the relays to the panel itself. But my solution is very serviceable.

Note, I left the original Cummins pump wiring connected. It still turns on and buzzes for the first 30 seconds of ignition on. I did read elsewhere online that replacing the pump with a simple relay (just the trigger-side terminals 85 and 86) will trick the computer in to thinking the pump is still connected, to eliminate any potential diagnostic fault codes. For now, I just used -10AN caps to close off that pump, but left the wiring.

I also took a moment to install 4 x threadsert(s) at the attachment points for the fuse and relay panel. The sheetmetal self-tappers were weak at best. One had fallen out in to the bottom of the panel. I didn't have long enough bolts to install all 4. I'll complete work in the PDU with installing that longer hardware.

My parts list:
Airdog Raptor 100 4G Universal pump set to 17psi. (this has an adjustable onboard regulator which can be set to up to 75 psi. I had them match what the 1998 to 2002 Cummins 5.9 uses), which is very similar. Interestingly, that pump also runs full-time in the pickup application.
4G is the fourth generation Air Dog pump and the tech said their most reliable.
I used push-style hose and ends. You could use braided or other. Just make sure the hose ends match the hose. And are diesel fuel compatible.

Assembly tricks:
1.heat the end of the hose you are assembling in a pot of boiling water for 3 minutes. Also, apply a little grease to the hose end. Remove from water and push firmly until the hose end is bottomed in the hose.
2. I also recommend installing one hose end and then carefully measuring the length. The hose is quite stiff and being off a little might cause issues, especially on the straight hose section. Too long and you could force it to kind and too short and you could tension it, weakening it.

-6 o-ring to -10AN adapter for the outlet side of the pump.
-10 o-ring to -10AN adapter for inlet side of the pump.
2 x -10AN straight hose ends (primary filter to pump inlet)
2 x -10AN 90-degree hose ends. (outlet of pump to secondary filter)
2 x -10AN caps (cap off old fuel pump)
4' of bulk -10 hose.
Optional:
-8AN female to male 45 coupler. The angle an extra length reduces tension on the fuel tank return line. Mine had some obvious tension - am assuming BB did this install. I am more careful myself.
-10AN female to male 45 coupler. Install this at the primary filter between the tank feed and the pump inlet. My line was under tension and the extra angle just helped align things.

In making my mount standoff I used 3/16" x 2" angle with 1/8" plate for the mounting flanges. I first made from 1/8" aluminum a template of the AirDog pump mount. Then used that to transfer to steel. If you don't weld, you might find some hefty aluminum (3/16") L-brackets for mounting solar panels which could be adapted. I'm picturing an L-bracket with a small aluminum vertical plate attached.

Hope this helps someone else.

One final note, AirDog and FASS (direct competitor) sell air-removing filtering setups for about $600. They have 2 on board filters with air removal features. They claim this makes the engine more efficient and reliable by stripping the air out. One could buy that setup and replace both primary and secondary filters. I figured Cummins designed this part well, so I left my as-is. That more expensive solution would be simpler to install and you'd just adapt the fuel tank line to the inlet and the outlet right to the CAPS pump.
Cheers,

Doug

[Robert Britton]

Nice work Doug, that coach is definitely in good hands!

[DW SD]

Originally Posted by Robert Britton

Nice work Doug, that coach is definitely in good hands!

Thanks, Robert!

Doug